The Xenotransplantation Core provides specialized, on-demand surgical services for the transplantation and evaluation of human fetal tissues in immunodeficient animals in support of the research projects carried out by the Formative Center. The core is responsible for the coordination of immunodeficient animal procurement (nude rats) with anticipated availability of fetal tissues, and sterile renal subcapsular or subcutaneous transplantation of appropriate fetal source tissue upon availability. Our group has demonstrated that fetal testis, handled and processed in the usual manner by hospital staff, is histopathologically responsive to selective toxicant exposure when implanted under the kidney capsule of nude rats. The Xenotransplantation Core facilitates the expansion of this past work into other fetal tissue types and environmental impacts by centralizing development of the xenografted animal model in support of the three primary research areas of the Formative Center: Metabolic Syndrome. Prostate Imprinting, and Lung Remodeling. The Xenotransplantation Core will function as the site of the initiation of the experiments carried out in the Formative Center's Research Projects by providing an on-demand service that coordinates with the Tissue Procurement Core to transplant fetal tissue as it becomes available into xenogeneic hosts. As such, the Core will maintain host animals for instant availability, and its personnel will have the shared responsibility of performing surgical requests within a time frame that allows confidence in graft viability upon implantation. The Xenotransplantation Core will pursue these Specific Aims: [unreadable] Specific Aim 1 - Provide animal surgery and model development services [unreadable] Specific Aim 2 - Interact with research investigators to initiate animal experiments in support of the Formative Center's research projects [unreadable] Specific Aim 3 - Implement current and emerging surgical techniques in xenotransplant model development and training of technical staff